Plural armature plunger type electromagnet



July 18, 1950 J. F. O'BRlEN ETAL PLURAL ARMATURE PLUNGER TYPE ELECTROMAGNET 2 Sheets-Sheet 1 Filed Dec. 9, 1947 July 18, 1950 J. F. OBRIEN ETAL 2,515,259

PLURAL ARMATURE PLUNGER TYPE ELECTROMAGNET Filed Dec. 9, 1947 2 Sheets-Sheet 2 I f 0 /9 n 4/0 5/ v 3 f- INVENTOR.

JOSEPH F. OBR/E/V Patented July 18, 1950 PLURAL ARMATURE PLUNGER TYPE ELECTROMAGNET Joseph F. OBrien, Lebanon, and John B. Cataldo, Annandale, N. J., assignors to John B. Pierce Foundation, New York, N. Y., a corporation of New York Application December 9, 1947, Serial No. 790,508

4 Claims. 1

This invention relates to electrical relays and to solenoid mechanisms. It constitutes an improvement on the subject matter disclosed and claimed in our similarly entitled co-pending application Ser. No. 740,144, filed April 8, 1947, now Patent No. 2,515,258.

The invention of the stated prior application involves a. solenoid mechanism, embodying a plunger assembly arranged for actuation by a solenoid coil, and latching mechanism arranged for correlative action with the plunger assembly. Such solenoid mechanism is there disclosed as a component part of an electrical relay, which is useful primarily in the remote control of an electrical circuit, for example, for the remote control, by push buttons as distinguished from switches, of a residential or industrial lighting system, the push button control of the relay being accomplished by a relative low voltage control circuit, say 24 volts, as compared with a 110 volt lighting circuit.

The present invention constitutes an improvement upon the invention set forth in the stated prior application, in that the plunger assembly is simplified and rendered capable of more economical production.

The plunger assembly of the prior solenoid mechanism, considered specifically, includes three separate plungers mounted end to end on a throwrod, the intermediate plunger being fixed to the throw-rod, and the other two plungers being slidable thereon relative to the fixed intermediate plunger. The throw-rod is of a non-magnetic material, such as brass, so as to be unaffected by the solenoid coil, but each of the three plungers is made of magnetic material, such as soft iron, and is directly influenced by the magnetic flux produced by the solenoid coil when energized. The two end plungers are normally held apart against respective limit stops by a spring so that there is freedom of movement therebetween for the intermediate plunger.

The above-described plunger assembly is arranged relative to the latching mechanism such that one or the other of the end plungers is latched against movement while the remaining one is free to move, the intermediate plunger being always positioned in proximity to the latter. Upon energization of the solenoid coil, the unl-atched end plunger and the proximately positioned intermediate plunger act as a single armature unit, moving to close the air-gap between the intermediate plunger and the other end plunger, and propelling the throw-rod to the opposite one of its alternative thrown positions.

The latching mechanism is so constructed and arranged as to automatically unlatch the previously latched end plunger and to latch the previously unlatched end plunger at the termination of any operation of the device as above-described, it being understood that, upon de-energization of the solenoid coil, the spring returns-to its limit stop positlonthat end plunger which moved conjointly with the intermediate plunger, whereupon the latch mechanism becomes effective thereon.

In accordance with the present invention the intermediate plunger is eliminated, and the end plungers are provided with skirt extensions which serve in place of the intermediate plunger as a path for the magnetic flux of the solenoid coil. The non-magnetic throw-rod is shouldered intermediate its length for the purpose of carrying out the purely mechanical function of the discarded intermediate plunger of compelling the throw-rod to accompany the gap-closing travel of either one or the other of the end plungers when the solenoid coil is energized. The operation is essentially similar to that of the prior construction, yet con siderable savings in cost result from the replacement of the magnetic intermediate plunger by the non-magnetic, intermediate shouldered portion integral with the throw-rod.

Thus, a primary object of the present invention is to simplify and reduce the cost of production of the device set forth in our stated prior application, without in any way impairing its operative efficiency.

Further objects and features will be apparent from the following detailed description of the preferred form illustrated in the accompanying drawings.

In the drawings:

Fig. 1 is a vertical sectional view taken partially on the line I'l, Fig. 2, but for the most part centrally through the device in its unenergized off, or circuit opening, position;

Fig. 2 is a horizontal section taken on the line 22, Fig. 1;

Fig. 3 is a horizontal section taken on the line 33, Fig. 1;

Fig. 4 is a view corresponding to that of Fig. 1, but illustratin the device in its energized on, or circuit closing, position;

Fig. 5 is a section taken on the line 5-5, Fig. 4;

Fig. 6 is a view corresponding to those of Figs. 1 and 4, but illustrating the device in its unenergized on position;

Fig. '7 is a corresponding view, but illustrating the device in its energized off position;

Fig. 8 is a fragmentary perspective view of a 3 portion of the latch mechanism drawn to an enlarged scale, the position of the mechanism corresponding to that of the upper part of Fig. 6;

Fig. 9 is a similar view, the position corresponding to those of the upper parts of Figs. 4 and 7;

and

Fig. 10 is another similar view, the position corresponding to that of the upper part of Fig. 1. Referring to the drawings, wherein the solenoid .mechanism of the invention is shown as embodied in an electrical relay in the manner of our stated prior application for patent: within the casing I is positioned a solenoid coil l1 surrounded by a magnetic shell comprising the parts l8, l9 and 20. The coil l l is adapted to be energized by electricity conducted thereto from a suitable source by the wires 22 and 23, the closing of the electrical circuit being controlled inany suitable manner, as, for instance, by a pushbutton (not illustrated) a The solenoid mechanism includes,besides the aforementioned coil and magnetic shell, a throwrod and plunger assembly; The throw-rod 3B is of non-magnetic material, such as brass, and has a shouldered portion 3iil intermediate its length. Secured at opposite ends of such throwrod are striker disks 32 and 33, provided for the purpose of operating latching mechanism referred to hereinafter. In addition to the striker disk 33 there is secured to the elongated shank 30a. of the throw-rod 39 a shorting bar assembly adapted to open and close an electrical load circuit. Such assembly includes a shorting ring 35 separated from the striker disk by a block of insulation 36. Shorting ring 35 is adapted to make and break with spaced electric terminals 26, 26 ofthe load circuit, depending upon the particular thrown position of the throw-rod 38.

A double-equilibrium, snap disk spring 34, anchored at its rim as illustrated, is interposed between striker disk 33 and the block of insulation 35, being thereby fixed to throw-rod 30 for imparting throwing force additional to that provided by coil energization.

The 'plungers slidably carried by the throw-rod 30 include, in the instance of the present invention, only two end plungers 4i! and 4! disposed on respectively opposite sides of the intermediate shouldered portion 38-4 of the throw-rod 30; and these are provided with skirt extensions 4lll and 4ll, which are adapted to meet about'the said intermediate shouldered portion of the throw-rod to close the air-gap between such plungers when the coil l! is energized, such skirt extensions are preferably, as illustrated, disposed circumferentially of the respective plungers, defining open pockets internally thereof.

Between the two plungers 4G and 4!, fitting within the respective open pockets thereof and encircling the intermediate shouldered portion 38l, of the throw-rod 36, is positioned a coil spring 44, which normally acts to separate the two plungers and create an air-gap between the respective skirt extensions thereof, see Figs. 1 and 6. The extent to which the plungers 40 and 4| are forced apart by the spring 44 is predetermined by respective bracket plates 42 and 43, such bracket plates providing mountings for respective latching mechanisms.

As in the instance of the stated prior application, the latching mechanisms each advantageously comprise a bell crank 59 pivoted on an axis which is substantially parallel with the corresponding bracket plate, such bell crank 51] having a trip-arm portion 54a extending into the 4 path of travel of the corresponding striker disk of throw-rod 30, and a depending actuating arm 50b which extends through a suitably provided aperture of the bracket plate into the vicinity of the trip arm portion Ela of a second bell crank Such second bell crank 5| is pivoted on an axis which is substantially perpendicular to the bracket plate, and has a latch arm Elb which is adapted to engage the flanged end, 40a or 40b as the case may be, of the corresponding plunger. Engagement of the latching arm MD with the corresponding plunger is brought about by reason of the actuation of the second bell crank 5| by the first bell crank 50.

In any unenergized condition of the device, the spring 44 maintains the two plungers 40 and 4! against the undersides of the respective bracket plates 42 and 43, the latter serving as limit stops. The snap disk spring 34 will be in either one or the other of its alternate position of equilibrium, and, depending upon the particular position of equilibrium, the throw-rod will be disposed so that its intermediate shouldered portion 3ll--I is against either one or the other of the plungers. Furthermore, that particular plunger against which the intermediate shouldered portion-3W4 of the throw-rod is positioned, is 'unlatched,"while the opposite plunger is latched against movement longitudinally of the throw-rod. '1

In the unenergized ofi condition of the'electrical relay device illustratedin Fig. 1, therthrowrod 3B'is maintained .in raised position by the snap disk spring 34, so that the shorting ringbreaks the load circuit represented b-y-the spaced terminal contacts 26, 26. The intermediate shouldered portion 3!ll of the throw-rod is thus positioned against the plunger 40, and the striker disk 32 causes its corresponding latchingmechanism to disengage the plunger 40, thereby-freeing it for movement longitudinally of the throw-rod.

Upon energization of the solenoid coil l'l, effected, for example, by pressing a push-button which is positioned remote from the electrical relay device in the control circuit embodying the lead wires 22 and 23, the magnetic flux causes the unlatched plunger to close the air-gap between the skirt extensions lll-l and 4l-l of the respective plungers, see Fig. 4. In so doing, plunger 4!] moves throw-rod 30 so as to upset the then position of equilibrium of the snap disk spring 34, whereupon such snap, disk spring operates to vigorously throw the throw-rod tothe position where shorting ring 25 closes the loadcircuit by making contact 'with the terminal contacts 26, 26. In this movement, the throw-rod 34 causes striker disk 33 to actuate the bell crank 5001 the corresponding latching mechanism, whereby-the bell crank 5| operated by its return spring v53, is caused to unlatch the plunger 4i from the latched condition of Fig. 3. At the sametime, the descent of striker disk 32 enables bell crank of the oppositely positioned latching mechanism to actuate the bell crank 5 l, by reason of the force of spring 52, into a preliminary'latching position relative to the plunger 40, see Figs. 5 and 9. l

The energization of the solenoid coil H is momentary, and, upon de-energization, see Fig- 6, the coil spring 44 forces plunger 40 outwardly to its limit stop position against the underside of bracket plate 42. Latching arm 5lb of the particular latching mechanism concerned had, prior to this movement of the plunger 40, been resiliently urged against the circumferential: rim of flange 40a by means of the spring 52 acting on bell-crank 50, see Fig. 9. Upon movement of the plunger 40 to its outward limit stop position, the latching arm Ib snaps into latching position under the flange 40a, see Fig. 8. This is the unenergized on condition of the device. It will be noted that the positions of the respective latching mechanisms are reversed as compared with the unenergized off condition of Fig. 1, and further, that the position of the intermediate shouldered portion 3fli of the throw-rod is opposite.

Upon energization of the solenoid coil I! to return the device to the unenergized ofi position of Fig. 1, the plunger 4! is impelled by the magnetic flux to close the air-gap between the skirt extensions of the respective plungers, the plunger 40 being held against movement by reason of the latching condition of its latching mechanism. Accordingly throw-rod is actuated to upset the equilibrium of snap disk spring 34, and to thereby cause a vigorous return of the throw-rod to its position of Fig. 1, whereby the shorting ring breaks with the terminal contacts 26, 26 and so breaks the load circuit controlled thereby.

From the above it will be seen that the operation of the present device is essentially similar to that of the corresponding device of our aforereferred to co-pending application Ser. No. 740,- 144. In the present instance, however, the skirt extensions of the respective plungers come together in the closing of the air-gap between the plungers, thereby providing a closed path for the magnetic flux of the solenoid coil l1 and elimmatin the need for a third plunger of magnetic material interposed between the two end plungers.

Whereas this invention is here illustrated and described with respect to a specific construction representing a preferred form of the instant invention, it should be understood that changes may be made in said construction and other constructions may be produced, on the basis of the teachings hereof, by those skilled in the art Without departing from the scope of the invention as defined by the following claims.

We claim:

1. In combination, a solenoid coil; a plunger arrangement disposed within said coil and operable thereby, said plunger arrangement comprising a long throw-rod of non-magnetic material having an intermediate shouldered portion, and a pair of plungers of magnetic material slidably positioned on said rod at respectively opposite sides of said intermediate shouldered portion for longitudinal movement along said rod, said plungers each having skirt extensions, the said skirt extensions being directed toward each other and adapted to meet about said intermediate shouldered portion of the throw-rod when the solenoid coil is energized to close the magnetic circuit through said plunger arrangement; respective stops fixed in relation to said solenoid coil limiting the extent of outward movement of said plungers; resilient means disposed between said plungers normally urging said plungers against their respective stops; a latching mechanism carried by each of said stops adjacent the nearer of said plungers, each of said latching mechanisms being spring-urged to engage the nearer of said plungers when in contact with its stop; and a striker disk on each end of said throw rod for striking an element of the adjacent latching mechanism to unlatch said mechanism.

2. The combination recited in claim 1 wherein the skirt extensions are disposed circumferentially of the respective plungers and define open pockets internally of said plungers; and wherein the resilient means is a coil spring Whose opposite ends fit into said open pockets of the respective plungers.

3. In an electrical relay, a solenoid coil; a plunger arrangement operable b said coil, said plunger arrangement comprising a long throwrod of non-magnetic material having an intermediate shouldered portion, said plunger assembly comprising, further, a pair of plungers of magnetic material slidably positioned on said rod at respectively opposite sides of said intermediate shouldered portion for longitudinal movement along said rod, said plungers each having recessed portions so as to form skirt extensions, the said skirt extensions being directed toward each other and adapted to meet about said intermediate shouldered portion of the throw-rod when the solenoid coil is energized; respective stops limiting the extent of outward movement of said plungers; resilient means normally urging said plungers against their respective stops; respective latching mechanisms disposed adjacent the said plungers for actuation alternately by spring means to latch and by said rod to unlatch the re spe-ctive plungers against movement longitudinally of the rod; and a snap disk spring operatively associated with said throw-rod for imparting impetus thereto in addition to said solenoid coil.

4. The combination recited in claim 3 wherein the skirt extensions are disposed circumferen tially of the respective plungers and define open pockets internally of said plungers; and wherein the resilient means is a coil spring whose opposite ends fit into said open pockets of the respective plungers.

JOSEPH F. OBRIEN. JOHN B. CATALDO.

REFERENCES @JITED The following references are of file of this patent:

UNITED STATES PATENTS record in the 

